JP3820898B2 - Step motor control apparatus and control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a step motor control device and a control method for driving a power transmission system including a gear.
[0002]
[Prior art]
The output torque T ₀ of the stepping motor is the maximum motor torque as described in documents such as “Stepping Motor Control Technology: 2000 Motor Technology Symposium Session A-5 Proceedings: Yoshiaki Fukuda, A5-2-1.” If Tmax and the load angle are θ, T ₀ = Tmax × sinθ.
[0003]
In addition, the bipolar drive of the two-phase HB step motor, which is a typical step motor, causes the current to flow simultaneously with the A-phase coil and the B-phase coil and changes the direction of current flow.
Current flows from A phase to / A phase and simultaneously from B phase to / B phase. (Hereafter referred to as A phase + B phase excitation)
Current flows from / A phase to A phase and simultaneously from B phase to / B phase. (Hereafter referred to as / A phase + B phase excitation)
Current flows from / A phase to A phase and simultaneously from / B phase to B phase. (Hereafter referred to as / A phase + / B phase excitation)
-Current flows from A phase to / A phase and simultaneously from / B phase to B phase. (Hereafter referred to as A phase + / B phase excitation)
The spatial distribution of torque in each excited state is as shown in FIG. In this way, each becomes a sine wave whose phase is shifted by π / 2.
[0004]
Normally, when driving a step motor, in consideration of an increase in load torque due to disturbance, an excitation phase in which the motor torque decreases from the maximum value is often selected and driven during acceleration. FIG. 3 shows the motor torque generated when driven in this way. The sine wave drawn by the thin line in FIG. 3 shows the torque generated when each phase is excited, and the torque drawn by the thick line is generated by switching the excitation phase.
[0005]
However, when the torque shown by the thick line in FIG. 3 is generated, the maximum torque is generated immediately after the start (position of π / 2 in FIG. 3), and then the torque decreases. In this case, a large torque is generated in a state where the gear is not engaged with the gear, and the torque is reduced after the gear is engaged and power is transmitted to the load. As a result, a loud noise is generated at the time of a gear collision, and as a countermeasure for disadvantageous transmission of torque to a load, for example, Japanese Patent Laid-Open No. 5-221080 discloses an example in which pressure is applied to eliminate backlash. In Japanese Patent Laid-Open No. 9-015680, the backlash amount is measured by using a gear sensor and the stepping motor is advanced in advance by the backlash amount to eliminate the influence of backlash at the time of starting. In order to eliminate the influence of backlash by the driving method, Japanese Patent Laid-Open No. 4-2619797 reduces the influence of backlash at the time of starting by driving the motor at a low voltage at the time of starting.
[0006]
[Problems to be solved by the invention]
However, in Japanese Patent Laid-Open No. 5-221080, a mechanical part for applying pressure, in Japanese Patent Laid-Open No. 9-015680, a sensor for measuring the position of a gear, and in Japanese Patent Laid-Open No. 4-261597, a drive voltage is switched. The need for means such as semiconductor parts has led to increased costs.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a step motor control apparatus according to claim 1 comprises:
In the step motor control device comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. Based on the initial position of the rotor, the excitation phase in which the motor torque increases from 0 is selected for the first pulse, the excitation phase in which the motor torque decreases from the maximum value is selected in the second pulse, and the commutation signal It is characterized by comprising signal output means for outputting.
[0008]
According to the first aspect of the present invention, an excitation phase in which the motor torque increases from 0 is selected in the first pulse based on the initial position, and commutation is started. After the second pulse, excitation in which the motor torque decreases from the maximum value. The phase is selected.
[0009]
According to a second aspect of the present invention, there is provided a step motor control apparatus comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. The control means selects an excitation phase in which the motor torque decreases from the maximum value until the backlash is eliminated based on the initial position of the rotor, and the next commutation is There is provided a signal output means for selecting an excitation phase in which the motor torque increases from 0, and thereafter selecting an excitation phase in which the motor torque decreases from the maximum value, and outputting the commutation signal.
[0010]
The control apparatus for a step motor according to claim 2 rotates the step motor until the backlash is eliminated, and selects the excitation phase in which the motor torque increases from 0 by the next drive, thereby reducing the backlash amount. Even when the step is larger than the basic step of the step motor, noise due to backlash can be eliminated.
[0011]
According to a third aspect of the present invention, there is provided a step motor control apparatus comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. And a step motor control device comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. In the step motor control apparatus, the control means selects an excitation phase in which the motor torque increases from 0 until the backlash is eliminated based on the initial position of the rotor, and thereafter the motor torque decreases from the maximum value. Signal output means for selecting an excitation phase and outputting the commutation signal is provided.
[0012]
According to the third aspect of the present invention, the step motor control device selects the excitation phase in which the motor torque increases from 0 until the backlash is eliminated, so that even when only the maximum value of the backlash amount is known. Noise caused by rush can be eliminated.
[0013]
According to a fourth aspect of the present invention, there is provided a step motor control apparatus comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. The control means includes a step of selecting an excitation phase in which the motor torque increases from 0 for the first pulse based on the initial position of the rotor, and the motor torque for the second and subsequent pulses. The method includes a step of selecting an excitation phase descending from a maximum value, and a step of outputting the selected commutation signal to the inverter means.
[0014]
In the invention according to claim 4, the same action as in claim 1 can be obtained.
[0015]
According to a fifth aspect of the present invention, there is provided a step motor control apparatus comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. In the step motor control apparatus, the control means selects, based on the initial position of the rotor, an excitation phase in which the motor torque decreases from the maximum value until the backlash is eliminated, A step of selecting an excitation phase in which the motor torque increases from 0, a step of selecting an excitation phase in which the motor torque decreases from the maximum value, and a step of outputting the selected commutation signal to the inverter means. It is characterized by having.
[0016]
Also in the invention according to claim 5, the same effect as in claim 2 can be obtained.
[0017]
According to a sixth aspect of the present invention, there is provided a step motor control apparatus comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. In the step motor control apparatus, the control means selects, based on the initial position of the rotor, the excitation phase in which the motor torque increases from 0 until the backlash is eliminated, and thereafter the motor torque The method includes a step of selecting an excitation phase descending from a maximum value, and a step of outputting the selected commutation signal to the inverter means.
[0018]
Also in the invention according to the sixth aspect, the same effect as in the third aspect can be obtained.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0020]
Example 1
FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a two-phase HB (hybrid) step motor applied as a driving means for rotating a developing device of a laser printer, for example. AC power is supplied from the drive circuit 20 to each phase coil of the step motor 10. The drive circuit 20 includes a DC power source 21 and an inverter 22 as inverter means connected to the DC power source 21. Here, the inverter 22 has two N-channel field effect transistors (hereinafter simply referred to as transistors) T _{a +} and T _a− between the positive power supply line L _P and the negative power supply line L _N and the drain of the transistor _{Ta +} is positive. the power line L _P, the transistor T _a- drain source, with are connected in series relationship connect the transistor T _a- source to the negative supply line L _N, the transistors T _{a +} and T _{a -} similarly to two N-channel field effect transistor in parallel (hereinafter, simply referred to as _{transistors) T / a +} and _{T / a-} are connected in series, the transistors _{T / a +} and _{T / a-} and likewise in parallel two N-channel field effect transistor (hereinafter, simply referred to as transistors) T b ₊ and T _b-are connected in series, these bets Njisuta _{T b +} and _{T b-similarly} to the two N-channel field effect transistor in parallel (hereinafter, simply referred to as _{transistors) T / b +} and _{T / b-has} a connection in series. _Free- wheeling diode that circulates current from the source side to the drain side between the drain and the source of T _{a +} , T _a− , T 1 _{/ a +} , T 1 _{/ a−} , T _{b +} , T _b− and T _{2 / b−} D _{a +} , D _a− , D _{/ a +} , D _{/ a−} , D _{b +} , D _b− and D _{/ b +} , D _{/ b−} are connected.
[0021]
In the case of A phase + B phase excitation, _{Ta +} and T1 _{/ a-} are turned on and current flows from A phase to / A phase. At the same time, _{Tb +} and T _{/ b-} are turned on and current flows from B phase / It is flowing to B phase. In the case of / A phase + B phase excitation, T _{/ a +} and T _a− are turned on and current flows from / A phase to A phase, and T _{b +} and T _{/ b−} are turned on at the same time, and current flows to B phase. To / B phase. In the case of / A phase + / B phase excitation, T _{/ a +} and T _a− are turned on and current flows from / A phase to A phase, and at the same time, T _{/ b +} and T _b− are turned on and current is It flows from B phase to B phase. In the case of A-phase + / B-phase excitation, Ta _{+ and} T _{/ a-} are turned on, current flows from A phase to / A phase, and T _{/ b +} and _Tb- are turned on simultaneously. It flows from B phase to B phase.
[0022]
An embodiment of the present invention will be described with reference to FIG. In FIG. 4, (a) shows the motor torque with respect to the rotor position, and (b) standardizes the rotor position with respect to time. The position where the maximum motor torque is 0 and the position delayed by π / 2 from the maximum position is − The position advanced by 1, π / 2 is shown as 1.
[0023]
In FIG. 4A, it is assumed that the rotor position at the time of stop is π / 2. In this case, if / A phase + B phase excitation is performed, the motor torque rises from 0. Therefore, / A phase + B phase excitation is selected as the excitation phase. Here, the rotor position π / 2 is a position that is delayed by π / 2 from the position (π) at which the motor torque is maximum in the case of / A phase + B phase excitation. Therefore, in FIG. Represents.
[0024]
The first pulse as shown in FIG. 4 is carried out _{T 11} time / A phase + B-phase excitation. Then the rotor position [pi, although the motor torque at time t ₁₁ selects the excitation phase of descending from the maximum value, as shown in FIG. 4 (a), the excitation phase of the motor torque decreases from the maximum value / A phase + B-phase since excitation of, _{T 12} performs continue / a phase + B-phase excitation time. Then select the rotor position 3 [pi] / 2, the excitation phase clogging / A phase motor torque decreases from the maximum value at time t ₁₂ + / B-phase excitation, performing excitation time T _13. Thereafter, the excitation phases are selected in the order of A phase + / B phase excitation, A phase + B phase excitation, / A phase + B phase excitation, / A phase + / B phase excitation, and T ₁₄ , T ₁₅ , T ₁₆ , T _{17 are selected.} Acceleration is performed while sequentially switching the excitation phase at intervals of.
[0025]
By selecting the excitation phase as described above, the motor rotates with a small motor torque in the gap between the gears due to backlash.
[0026]
(Example 2)
If the backlash amount is larger than the basic step angle of the step motor, the driving by the above method may be performed after driving until just before the gear meshes. For example, FIG. 5 shows an embodiment in which the backlash of the gear is between 3 and 4 as the basic step number of the step motor. In FIG. 5A, it is assumed that the rotor position when stopped is π / 2. First, an excitation phase that decreases from the maximum motor torque, that is, A phase + B phase excitation is selected. First pulse performs time _{T 21} the A-phase + B-phase excitation. Then the rotor position [pi, excitation phase switching at time _{t 21,} performed / A phase + B-phase excitation time _{T 22.} Then the rotor position 3 [pi] / 2, switching the excitation phase at time _{t 22,} performs / A Phase + / B-phase excitation time _{T 23.} Up to this point, the step motor rotates for 3 basic steps. Next, an excitation phase in which the motor torque increases from 0, that is, A phase + B phase excitation is selected. Rotor position 2 [pi, performs time _{T 24} the A-phase + B-phase excitation performs phase switching at time _{t 23.} Then the rotor position 5 [pi] / 2, although the motor torque at time t ₂₄ it is necessary to select an excitation phase which decreases from the maximum, as shown in FIG. 5 (a), the excitation phase of the motor torque decreases from the maximum phase A since + B-phase excitation is performed time _{T 25} the a-phase + B-phase excitation continues. Next, at the rotor position 3π, at time t ₂₅ , the excitation phase in which the motor torque decreases from the maximum, that is, / A phase + B phase excitation is performed for a time T ₂₆ . Later, / A phase + / B-phase excitation and select it accelerates performs time T ₂₇ energized.
[0027]
By selecting the excitation phase as described above, even when there is a backlash exceeding the basic step of the step motor, the motor can be rotated with a small motor torque in the gap between the gears.
[0028]
Example 3
Moreover, although the maximum value of the backlash amount is known, FIG. 6 shows an embodiment in which the backlash amount changes depending on conditions. FIG. 6 shows a case where the maximum backlash amount is 4 steps. In FIG. 6A, it is assumed that the rotor position when stopped is π / 2. First, an excitation phase in which the motor torque increases from 0, that is, / A phase + B phase excitation is selected. First pulse do _{T 31} time / A phase + B-phase excitation. Then the rotor position [pi, switching the excitation phase at time _{t 31,} performs / A Phase + / B-phase excitation time _{T 32.} Then the rotor position 3 [pi] / 2, switching the excitation phase at time _{t 32,} performs A-phase + / B-phase excitation time _{T 33.} Then the rotor position 2 [pi, excitation phase switching at time _{t 33,} performs A-phase + B-phase excitation time _{T 34.} Up to this point, the step motor has been rotated for four steps, and the backlash has been eliminated. Then the rotor position 5 [pi] / 2, although the motor torque at time t ₃₄ it is necessary to select an excitation phase which decreases from the maximum, as shown in FIG. 6 (a), the excitation phase of the motor torque decreases from the maximum phase A since the + B-phase excitation, time _{T 35} performs the a-phase + B-phase excitation continues. Thereafter, selection is made in the order of / A phase + B phase excitation, / A phase + B phase excitation, and driving is performed at time intervals of T ₃₆ and T ₃₇ to accelerate.
[0029]
By selecting the excitation phase as described above, even when the backlash amount is not clear, the motor can be rotated with a small motor torque in the gap between the gears.
[0030]
Here, since the step motor is controlled in an open loop that does not feed back the rotor position, the excitation time is stored as a value command pulse train by storing the value measured using the actual machine or the value obtained by calculation in a memory or the like. You can do it.
[0031]
【The invention's effect】
As described above, according to the inventions according to claims 1 and 4, the motor torque is applied to the load by backlash by selecting and driving the excitation phase in which the motor torque increases from 0 from the initial position of the step motor. While it is not transmitted, it can be driven with a small torque, and the motor torque becomes maximum after the gears mesh with each other, so that noise can be reduced and the torque transmission efficiency to the load is also increased.
[0032]
According to the second and fifth aspects of the invention, even when the backlash is larger than the basic angle of the step motor, noise can be reduced and the torque transmission efficiency to the load can be increased.
[0033]
Further, according to the third and sixth aspects of the invention, even when the backlash amount changes depending on conditions, it is possible to reduce noise and increase the torque transmission efficiency to the load.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a torque space distribution in an excited state.
FIG. 3 is an explanatory diagram showing torque generated by a conventional driving method.
FIG. 4 is an explanatory diagram showing a specific example of an excitation phase selection method.
FIG. 5 is an explanatory diagram showing a specific example of an excitation phase selection method when the backlash amount is known.
FIG. 6 is an explanatory diagram showing a specific example of a method for selecting an excitation phase when the maximum value of the backlash amount is known.
[Explanation of symbols]
10 2-phase HB (hybrid) step motor 20 driving circuit 21 a DC power source 22 inverter 30 control circuit _{D a +} freewheeling diode _{D a-} freewheeling diode _{D / a +} freewheeling diode _{D / a-} freewheeling diode _{D b +} freewheeling diode _{D b-wheel} diode D _{/ b +} freewheeling diode _{D / b-wheeling} diode _{T a +} transistor _{T a-} transistor _{T / a +} transistor _{T / a-} transistor _{T b +} transistor _{T b-transistor T / b +} transistor _{T / b-transistor}

Claims (6)

In the step motor control device comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. Based on the initial position of the rotor, the excitation phase in which the motor torque increases from 0 is selected for the first pulse, the excitation phase in which the motor torque decreases from the maximum value is selected in the second pulse, and the commutation signal A step motor control apparatus comprising a signal output means for outputting. In the step motor control device comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. Is based on the initial position of the rotor, selects the excitation phase in which the motor torque decreases from the maximum value before the backlash is eliminated, and the next commutation selects the excitation phase in which the motor torque increases from 0, Thereafter, the step motor control device is provided with a signal output means for selecting an excitation phase in which the motor torque drops from the maximum value and outputting the commutation signal. In the step motor control device comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. Selects the excitation phase in which the motor torque increases from 0 until the backlash is eliminated, and selects the excitation phase in which the motor torque decreases from the maximum value based on the initial position of the rotor. A step motor control apparatus comprising a signal output means for outputting. In the step motor control device comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. A step of selecting an excitation phase in which the motor torque increases from 0 in the first pulse based on an initial position of the rotor, a step of selecting an excitation phase in which the motor torque decreases from the maximum value after the second pulse, And a step of outputting the selected commutation signal to the inverter means. In the step motor control device comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. Based on the initial position of the rotor, select the excitation phase in which the motor torque decreases from the maximum value until the backlash is eliminated, and the next commutation selects the excitation phase in which the motor torque increases from 0 A step motor control method, comprising: a step of selecting an excitation phase in which the motor torque decreases from a maximum value thereafter; and a step of outputting the selected commutation signal to the inverter means. . In the step motor control device comprising: inverter means for driving the step motor based on the supplied commutation signal; and control means for generating a commutation signal supplied to the inverter means based on the drive command. A step of selecting an excitation phase in which the motor torque increases from 0 until the backlash is eliminated, and a step of selecting an excitation phase in which the motor torque decreases from the maximum value based on the initial position of the rotor; And a step of outputting the selected commutation signal to the inverter means.

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